Selective precipitation of bis(chloromethyl) durene from toluene



Oct. 10, 1961 w. G. DE PIERRI, JR, ETAL 3,004,078

SELECTIVE PRECIPITATION OF BIS(CHLOROMETHYL)DURENE FROM TOLUENE Filed July 14, 1959 DURENE FORMALDEHYDE HYDROCHLORIC ACID AND CATALYST 1 IL. 80 CHLOROMETHYLATION ZONE 36 DISCHARGE STREAM AQUEOUS PHASE SETTLING ZONE 38 2 0+ 32 CHILLING ZONE 5 AQUEOUS PHASE FILTRATION ZONE IPARTICULATE SOLIDIFIED 46 REACTION PRODUCT 14 SOLUBILIZATION HEATER TOLUENE HEATER-" ZONE V 49 r TOLUENE SOLUTION 1 WATER IN NE 56 SETTL G Z0 A K NE WASH LIQUID BEWATERED TOLUENE SOLUTION CRYSTALLIZATION ZONE GBWT-SLURRY 78 HIGH PURITY BIS(CHLOROMETHYLI 70 DURENE FILTRATION 20m: 12

74V FILTRATE 76 7 RECYCLE TOLUENE DISTILLIZATION ZONE 5 80 78 INVENTORS.

WILLIAM G. De PIERRLJIZ. BY HAROLD W.EARHART, puns:

ATTORNEY United at s aw Q This invention relates to a process for the purification of bis(chloromethyl)durene. More particularly, this invent-ion relates to a solvent crystallization process for the substantially selective recovery of high purity bis- (chloromethyl) durene.

Bis(chloromethyl)durene is a difunctional compound which may be prepared by the dichloromethylation of durene. When durene is subjected to dichloromethylat-ion conditions, the chloromethylation reaction product comprises a mixture of compounds, including bis(chloromethyl) durene, from which the bis(chloromethyl) durene is recovered only with difliculty.

It has now been discovered that substantially selective recovery of the bis(chloromethyl)durene may be accomplished by dissolving the chloromethylation reaction prodnet in hot toluene, by thereafter cooling the thus formed solution to selectively precipitate the bis( chloromethyl)- durene and by thereafter recovering the precipitated bis- (chloromethyl)durene.

When this is done, bis(chloromethyl)durene of high purity, 95 to 99 percent, is obtainable with comparative ease. Solvents closely related to toluene are not satisfactory for this purpose. For example, benzene, because of its low boiling point, high freezing point, and toxicity, presents serious problems when its utilization as a solvent is attempted. Xylenes, on the other hand, are reactive with bis(chloromethyl)durene whereby a high purity product is not selectively obtainable.

The invention will be further illustrated in connection with the accompanying drawing wherein the single figure is a schematic flow chart illustrating a preferred mode of the present invention.

Turning now to the drawing, durene, formaldehyde, hydrochloric acid and a suitable chloromethylation catalyst such as zinc chloride, stannic chloride, boron trichloride, antimony pentachloride, etc. are charged to a chloromethylation zone 10 by way of charge lines 12, 14 and 16.

Briefly, the durene may be reacted with from about 2 .to 6 mols of formaldehyde per mol of durene and from about 1 to 2 mols of hydrochloric acid per mol of formaldehyde under chloromethylation conditions including a temperature within the range of about 10 to about 150 C. for a reaction time within the range of about 0.5 to 5 hours. The chloromethylation reaction is described in greater detail in De Pierri and Earhart application Serial No. 717,225 filed February 24, 1958, now abancloned, and entitled Chloromethylation Process, and in copending De Pierri and Earhart application Serial No. 826,994 filed on an even date herewith and entitled Method for Chloromethylating Aromatic Hydrocarbons.

The chloromethylation-reaction product would normally be comprised of an aqueous phase and an oil phase. The oil phase will normally comprise uureacted durene, monochloromethyl durene and other by-products and the desired bis(chloromethyl) durene. The aqueous phase will normally comprise water, uureacted formaldehyde, hydrochloric acid and the chloromethylation catalyst.

In accordance with the above-illustrated embodiment of the present invention, a discharge stream of the chloromethylation product is discharged from the chlorometh- 2 ylation zone by way of H by a valve 22 leading to a settling zone 24.

Within the settling zone 24, phase separation is mitted to occur in order to separate the aqueous phase 5 from the oil phase. The aqueous phase is discharged from the settling zone 24 by way of a discharge line 26 for further processing, as desired. Thus, the aqueous phase may be charged to a recovery zone (not shown) of any suitable construction wherein catalyst, hydro-' chloric acid and formaldehyde may be recovered for recycle and wherein excess water (e.g. water reaction) may be removed from the system.

The oil phase is discharged from the settling zone 24 by way of a line 28 controlled by a valve 30 leading to a chilling zone 32 wherein the oil phase may be admixed with a cold diluent such as water charged by a line 34 and rapidly chilled with agitation in order to form a slurry of beaded chloromethylation product in the diluent. Such a process is described in greater detail in copending De Pierri and Earhart application Serial No. 827,087 filed of an even date herewith and entitled Method for Recovering Solid chloromethylation Products."

In the illustration, the valves 22 and 30 in the lines 20 and 28- may be closed, whereby the settling zone 24 will be by-passed and instead the total reaction product.

from the chloromethylation zone 10 may be charged to the chilling zone 32 by way of a branch line 36 controlled by a valve 38. In this case, the aqueous phase of the slurry formed in the chilling zone 32 will contain water soluble components of the chloromethylation reaction product stream including formaldehyde, hydrochloric acid and catalysts.

discharged therefrom by way of a line 40 leading to a filtration zone 42 or any suitable construction wherein the beaded chloromethylation product is recovered from the slurry. The aqueous phase of the slurry is discharged from the filtration zone 42 by way of line 44 for further processing, as desired.

In accordance with the present invention, the particulate solidified beaded chloromethylation reaction product is discharged to a solubilization zone 46 by way of conduit 48 and is there dissolved by hot toluene introduced into the zone 46 by way of a toluene charge line 49 containing a heater 50. It is generally preferable to utilize refluxing toluene which will dissolve about 50 percent of its weight of product. However, this is not absolutely necessary, provided that an amount of toluene is utilized for the temperature involved, to substantially Completely dissolve the chloromethylation product. Thus,

for example, the solubilization zone may be maintained. at a temperature within the range of about t0.

The toluene solution of chloromethylation product is discharged from the solubilization zone 46 by way of a line 52 leading to a settling zone 54 wherein any water which may have been occluded in the beaded chloromethylation product is separated for removal by way of discharge line 56. Thus, the provision of the settling zone 54 provides for substantially complete dewatering o the product.

In accordance with the modified form of the invention, the toluene solution is treated with an aqueous alkaline wash liquid introduced into the line 52 by way of a branch line 58 controlled by valve 60 in order to neutralize any residual hydrochloric acid which may be present (e.g., an aqueous solution of sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc.). In this case, the alkaline wash liquid is removed from the settling zone 54 by way of the line 56.

The dewatered toluene solution is next withdrawn from the settling zone 54 by way of a line 62 leading to a Patented Oct. 10, 1961 a discharge line 20, controlled s ows ,3 acne. .5.. the ein. he tolue e solu i n cooled at a temperature range of about by way of a cooler 66 of anyfdesired construction whereprecipitated.

1? 4;!!- Qi; i i hlqr methvll urene. dis har ed pmfihe cr s all zat n. Anne. by we at a n 6 ead: 18! fi t ti zone mnh r in the i lq omst y dn sae parated om th m t r. iquor;

h h p y. b tqhlomm thyndut s. ecov r d. ig way' i; a, isszh e. i e. 72 a d; the. a is i charged y filti e. wh ch p si b yl a s distillation zone 75. Within the distillation zone;76 the fraction which is recycled byway of; a, recycle 78 to the q u c r n 49, and a eavie cy l t m taining; unreacted durene. and monochloromethyl durene, and; a, m nor amount er unreacted bis.(chloromethyl) dgrene which isrecycledby way of a recycle line 80 to the durene charge line 12, A purge stream 82 may be provided, to prevent an, undue buildup of reaction byproduct such asdiphenyl methanes in the system.

Ihe invention will be further illustrated by the followspecific examples. which. aregiven by way of illustra tion and no ta s limitat ions.-on the. scopeoi this invention.

Example I ar-sha es i lorc iet lat dfiq Pr e. onretl'uil)ilur r s;

The dichloromethylation of durene was carried out in the following manner: a "3;ne'cl ;ed "Morton stirring flask" tirrer having a wat er jacketed" following mate als iw'er'e lia'rg v the Durene 805, 6.,moles)-. Zincclnoride anhydrous) 818g. (6 moles) Eormalin (37 percent) "260ml. (30 moles).

ixdro ricaeid.(3 .per nt) 33.20. mol s.)- lion ioniodetergentcn;...-., 74111..

Z The mixture in the fl aslr wasagitated andwasheated at 10 hours. Atthe end of the 10 hour period,'heating was discontinued and" about "4 liters ofwate'r-ice mixture was added'to the flask with vigorous: agitation. This wasdonej ifi oider'toinsure thatth' solid producfwould be in the" for at least 24 hours. The recrystallization was carried out in open-top porcelam blending vessel equipped with an air drive stirrer,

afcopper tubing steam coil and a tight'fitting lid. Into this've ssel wasplaced 'gallons'oftohien'e. The toluene was heated to" 100 C. andthe crude "reaction product" was added and dissolved. After solution was complete,

a solution of 500 g. of sodium carbonate and 3 l. of water hiueh c n nethz mqteae. s. s bsta ia selectively fill m y bev separated into a light high purity. toluenewas added as -a wash solution to remove any residual hydrochloric acid. 'Sti'rring was stopped and the aqueous phase withdrawn. The solution in the blending vessel Wa'sfthen allowed to cool to 'room'temperature and the crystals which formed were separated by centrifuging. The white crystals (85 kg.) which'we're obtained were found to be bis(chloromethyl) durene of 97 percent purity.

Examination of the' 'r'nother liquor from the second crystallization indicated that it contained a large amount of material still dissolved in the toluene. thedissolved m-ateriaI-shOWed-it to be chloromethyldurene of 92 percent purity, the principal impurity being bis(chloromethyndurene.

' Example II.

Example I was repeated with oneexception. Solvent.

Analysis of xyle e were rtil aesl ar. he simi arities. ta. n lat of toluene." In this'casefthe mother liquor containe about 8 percent of diphenyl mthanes formed by reaction of the bis(chloromethyl)durene with the xylenes. There was no such reaction in Examplelwhen toluene was used as thesolvent. i

What is, claimed. is:

1. A method-tori recovering high purity bis(chloromethyl)durefi 'e frdiri a crud'jsoliddurene' chlorome t'hylat'ion' reactionproductcontaining "are same which, compn'ses dissolving said chlorometliylationi product in toluene at a temperate-re ns spen 60"C., cooling said thus prepared toluene'"solution to a temperature within therange (rt-about 10 to .35 C. to selectively precipitate said bis(chloromethyDdurene. and recovering said precipitatedbis(chloromethyDdurene.

2. In a method whereindurene isreacted with formaldehyde and hydrochloric acid in the presence of a chloromethylation catalyst to provide a reaction mixture comprising an aqueous phase and a crude product phase containing bis(chloromethyDdurene, in which said aqueous. phase, is removed from said product phase. to provide a dewatered product. phasecornprising solid durene chloromethylation products, the. improvement which comprises'heating said productphaseat a temperature within. the range of about. to about..ll0- C. in thepresence of an amount. of toluene sufficient to dissolve said. P uct phase, Cooling said; thus prepared toluene solution to a temperature withinthe rangeof about -10 to 35 C. to selectively precipitatebis(chloromethyl) durene. and recovering saidprecipitated bis(chloromethyl) durene.

3. A method as in claim 2 wherein thelprecipitated bis(chloromethyl)durene is, recovered. by filtration, wherein the fil.trate 'from which filtration stepis fraov tionatedginto a toluene fraction anda'recycle fraction. and-wherein said recycle, fraction. isgtreated with addi-. tional quantities of.;formaldehyde andhydrochloric acid-1 in. the presence .of 1a chloromethylation catalyst to pro! vide an additional" quantityof .bis.( chloromethyl)durene.

"4f. Ina 'C.0I1tlII11G11S.T;pIOCB SS. jf01 the. production of high purity bis(chloromethylldurene. by. the; continuous reactionjof durene with formaldehyde.andrhydrochloric-acid in a.. reaction. zonj. together. with a chloromethylation catalyst, whereby areaction mixtureiis formed comprising an aqueous phase and a crude productphase, in which a stream "of reaction. mixture is 'continuously withdrawn from saidrreaction zone and'continuously separated into an aqueous phaseand asolid product phase, the improvementwhich comprises continuouslydissolving said prod ucjtphase in toluene at a temperature in excess of about 80 C. in a solubilizing zone, continuously washing saidtoluenesolutionwith an alkaline aqueous wash liquid at a temperature above about. 80 C.,' continuously 'sepa rating said. aqueouswash liquidfrdm said toluene solution, 'continuouslycooling said. toluene solution to a temperature within therangeot about 10 to 35 C. to selectively precipitate bis(chloromethyDdurene, whereby a slurry is formed-containing crystallized bis(chloromethyD durene, 'c6ntinuously"'filtering said slurry in av filtration zonejto recover high purity bis(chloromethyD- durene, continuously fractionating thefiltrate from said filtration ,z hsimq ajtolu'ene fi'actionand arecycle frac ash oomprlsin'g fdurjenefand durene. chloroznethylationproductecontiiiiiously recycling said toluene fraction to said solubilizing ..zo,ne an d continuously recycling said i i st ilt i-r sstis zeasr Rfetences Cited in the filecf this-patent N ED... TATES, A EN 2,s73, 299.; Mikeska, Feb.10, 1959 

1. A METHOD FOR RECOVERING HIGH PURITY BIS(CHLOROMETHYL)DURENE FROM A CRUDE SOLID DURENE CHLOROMETHYLATION REACTION PRODUCT CONTAINING THE SAME WHICH COMPRISES DISSOLVING SAID CHLOROMETHYLATION PRODUCT IN TOLUENE AT A TEMPERATURE IN EXCESS OF ABOUT 60*C., COOLING SAID THUS PREPARED TOLUENE SOLUTION TO A TEMPERATURE WITHIN THE RANGE OF ABOUT -10* TO 35*C. TO SELECTIVELY PRECIPITATE SAID BIS(CHLOROMETHYL)DURENE AND RECOVERING SAID PRECIPITATED BIS(CHLOROMETHYL)DURENE. 